using switchcraft 12a's on a marshall JCM800 build

[Curranproducer]

I dislike the cliff jacks and really like the 12a's from switchcraft. I want to wire up my new JCM800 build with 12a's. I am having some difficulty wrapping my little noodle around doing this while looking at the schematic. please help!

[martin manning]

If you are wanting to do a switched cascade set up like e.g. a 2204 then the "high" jack will have to be something more than a 12A. It needs another switching contact to un-ground the second triode.

[Curranproducer]

so this drawing will not work then? and please ignore the "destination" notes for each jacks HOT connection. I know they are incorrect

[Curranproducer]

I also realize in the drawing the 68k is on the wrong lead and needs to be on the HI Gain not the low

[martin manning]

In your sketch the high input feeds both grids (parallel, not series). See http://mhuss.com/MyJCM/JCM800_2204.pdf

[Curranproducer]

isn't that schematic standard there? that is the one I have built off of for a few of these 800's I mis-word-spoke aboot the cascading.

[Curranproducer]

I also moved the standby switch AFTER the rectifier diodes, and 1st 50+50 filter stage. I was looking at a few other schematics of different builds and saw this going on, it should take stress off of the tubes and stuff the way I have it routed now correct?

[martin manning]

You could connect 12A's as shown below and get the cascaded/Stg 1 bypassed arrangement. I don't know what the consequences of leaving out the grounding contacts will be, though. Maybe some extra noise or popping when you plug in?

I don't believe moving the standby after the reservoir will make too much difference. Maybe a bit less peak surge current through the rectifiers, but a bit more through the line fuse when the main power is switched on.